Theroux's most recent travelogue is "Deep South: Four Seasons on Back Roads."

MUST-HAVES: I never travel without at least three books, usually novels, not current ones but classics — nearly always paperbacks that I will give away after I've read them. Always a notebook with a good binding. Always two or three pens — specifically Lamy ballpoints. Driving in the deep South for my book, I always had bottles of wine in the back of my car and often food, for those late stops in remote motels where they have microwaves.

COULD USE: Probably a new hat, called the Voyager — made by Lock & Co. Hatters in London. Mine is very battered. You can roll them up and pack them.

TO GIVE: It all depends on the person. For a new friend, perhaps a book of mine related to a distant place, my novel "The Lower River" (set in Africa), or "The Elephanta Suite" (set in India). For an old friend, a classic book, "Madame Bovary." For someone I loved, I would buy a piece of luggage from Glaser Designs in San Francisco.

MUST-HAVES: I pack things that are easy to carry and fashionable at the same time — items that make me feel good and look good, without complication or stress. A cozy black sweater. Elegant flats. And a wrap from my scarf collection (SheilaJohnsonCollection.com), which is great for staying warm on the plane and can accessorize any outfit.

COULD USE: I'd love a warm, oversized bathrobe. It's like wrapping yourself in comfort, wherever you are. To me, when I'm traveling, there's nothing better to come back to than a soft, cozy bathrobe you can just sink into and relax in — especially after a long day out hiking or sightseeing. One of my favorite bathrobe brands and styles is UGG's Duffield.

TO GIVE: A great, versatile piece of luggage is the best gift I can imagine. TUMI luggage is my personal preference. I like the weight, expansiveness and style (like the Tegra-Lite extended trip packing case). Walt Whitman once wrote, "every cubic inch of space is a miracle" — and when you're traveling, that's certainly the case!

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IRFAN AHMAD: MY TRAVEL PARTNER IS MY PHONE

Ahmad created the Irhal app for Muslim travelers, which includes 90-plus city guides with halal restaurants, mosques and prayer timings for each city.

MUST-HAVES: My No. 1 travel partner is now my phone. In the past, not unlike the 108 million fellow Muslims who travel every year, I needed a compass to find the direction of Mecca to say my prayers in a new city. Today, my phone with the Irhal app has a built-in compass.

ALSO: My navy blue Sperry top-siders — the original two-eye boat shoe that can look cool on the beach and casually elegant in any party I need to attend while traveling. And of course, for that unexpected formal event, a Polo Ralph Lauren navy blue sport coat/blazer with brass buttons that even makes a T-shirt look respectable.

COULD USE: I need to replace my pull-along bag which I use to protect my laptop while traveling. ... I am looking for that perfect saddle-leather antique-looking, weather-beaten bag with modern spinner wheels that glide across the aisle with ease. The perfect blend of rugged leather and modern comfort.

TO GIVE: A GoPro for the adventure-seeker who loves bungee-jumping or zip-lining. A phone battery backup for the always-connected millennial.

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KAREN MAGEE: ALWAYS PACK A CHANGE OF CLOTHES

Magee is a hotelier and founder of Young Travel Professionals, with over 10,000 members globally.

MUST-HAVES: Moisturizer. To go from a long plane ride straight to a day full of meetings, especially when it's a red eye, I'll use my favorite Fresh Umbrian Clay oil-free lotion.

I always pack a change of clothes in my carry-on. My usual? A Black House White Market slip dress. The material doesn't wrinkle and the dress can easily roll up into a tiny ball, perfect for a small bag. The retailer comes out with new patterns every season.

COULD USE: A technology company called Bluesmart is creating a carry-on bag that connects to your phone. It can weigh itself, charge your devices in an easy-to-access front pocket, alert you if you are outside of a certain vicinity and track the bag if you can't find it.

TO GIVE: Passes to the lounge, business class upgrades, hotel room upgrades or an excursion when they get to their destination. For ladies, a travel jewelry case. For guys, The Art of Shaving has travel kits that my husband can't travel without.

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Follow Beth Harpaz at Twitter.com/AP_Travel. Her work can be found at http://bigstory.ap.org/content/beth-j-harpaz